The present invention relates to an apparatus for evaluating quality of coffee beans, particularly, raw coffee beans.
A coffee berry is called a "cherry" at the another name, and has a fleshy or pulpy husk on the outside and a sarcocarp on the inside. Further, the coffee berry has an endocarp and a silver skin, and an albumen at the extremely center point. Raw coffee beans generally circulated under commercial transactions are those from which slight parts of the endocarp and the silver skin are removed slightly, and moisture content of the raw coffee beans is 13% to 15%. The raw coffee beans are high or strong in viscosity and elasticity, and it is difficult to pulverize the raw coffee beans uniformly.
Generally available coffee beans are those in which flesh is removed from a completely ripe coffee fruit and in which dried and chosen seeds (raw coffee beans) are roasted. It is said that a taste of coffee such as acidity, bitterness and smell or aroma depends upon difference in condition of the roasting. On the other hand, however, it is also known that considerable difference in taste is caused by the quality of raw coffee beans due to difference in kind and cultivation of the coffee. That is, taste and flavor of the coffee are primarily decided by difference in quality and roasting condition of the raw beans, but if the roasting condition is the same, the taste of coffee is substantially decided by the quality of raw beans.
By the way, conventionally, judgment on the taste of coffee is based on a so-called sensuous examination in which roasted beans are pulverized, hot water is added to the pulverized beans, and operators actually taste the water. Accordingly, a plurality of operators and a long time are required for doing full justice to the judgment. Further, since the judgment is effected on the basis of the palate or taste having individual difference, it is difficult to say that the judgment is effective and unchangeable.
It is also conducted that caffeine is drawn out of roasted coffee beans, and content of the caffeine is measured chemically. This is not evaluation of the quality per se of the coffee beans.
In summary, it is the present condition that no trial or attempt is made to carry out measurement or evaluation at the stage of raw coffee beans.
Below table indicates scientific measurement and analysis of chemical components of raw coffee beans and roasted coffee beans.
TABLE ______________________________________ (%) PRO- CANE CHLOROGENIC TEIN SUGAR ACID ______________________________________ RAW BEANS 11.6 7.3 7.6 ROASTED BEANS 3.1 0.3 3.5 ______________________________________ REDUCING CAFFEINE TRIGONELLINE RESIN SUGAR ______________________________________ 1.2 1.1 11.4 0.7 1.3 0.7 11.9 0.5 ______________________________________ HEMI- UNKNOWN CELLULOSE CELLULOSE LIGNIN COMPONENT ______________________________________ 23.0 12.7 5.6 14.0 24.0 13.2 5.6 31.7 ______________________________________
According to the above table, it is understood that components considerably reduced after having been roasted are protein, cane sugar and chlorogenic acid. It is considered that these three components are primary elements which create taste and flavor by heat reaction at the time of roasting.